Castration (also known as orchiectomy or orchidectomy) is any action, surgical, chemical, or otherwise, by which an individual loses use of the testicles: the male gonad. Surgical castration is bilateral orchiectomy (excision of both testicles), and chemical castration uses pharmaceutical drugs to deactivate the testes. Castration causes sterilization (preventing the castrated person or animal from reproducing); it also greatly reduces the production of certain hormones, such as testosterone. Surgical castration in animals is often called neutering.
The term castration is sometimes also used to refer to the removal of the ovaries in the female, otherwise known as an oophorectomy, or the removal of internal testes, otherwise known as gonadectomy.
The equivalent of castration for female animals is spaying. Estrogen levels drop following oophorectomy, and long-term effects of the reduction of sex hormones are significant throughout the body. Castration of animals is intended to favor a desired development of the animal or of its habits, as an anaphrodisiac or to prevent overpopulation. As above, see neutering for more information on castration of animals.
The term castration may also be sometimes used to refer to emasculation where both the testicles and the penis are removed together. In some cultures, and in some translations, no distinction is made between the two. This can cause confusion.
Castrated males were recorded in Assyria 3000 years ago; causes were punishment and to produce eunuchs. The Italian practice of castrating boys to make them soprano singers was nominally ended only in 1878 by a papal order. A trade in castrated boys to be used in Muslim harems is believed to still exist.